US Patent 9496363 FinFET isolation structure and method for fabricating the same

A semiconductor device includes a semiconductor device and a semiconductor fin on the semiconductor substrate, in which the semiconductor fin has a fin isolation structure at a common boundary that is shared by the two cells. The fin isolation structure has an air gap extending from a top of the semiconductor fin to a portion of the semiconductor substrate. The air gap divides the semiconductor fin into two portions of the semiconductor fin. The fin isolation structure includes a dielectric cap layer capping a top of the air gap.